Pronunciation: (thum'nāl"), [key]
1. the nail of the thumb.
2. anything quite small or brief, as a small drawing or short essay.
3. Print.a small, rough dummy.
4. Also called porkchop. Journ., Print.a half-column portrait in a newspaper.
quite small or brief; concise: a thumbnail description of Corsica.
to make a thumbnail sketch or description of.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.